Integral facet cryopump, water vapor pump, or high vacuum pump

A cluster tool includes processing chambers, internal robots to manipulate wafers, and load lock chambers where wafer exchanges take place from the load lock chamber to the transfer chamber. The transfer chamber is held at a low vacuum pressure. The load lock chamber is connected to the transfer chamber by a valve. The load lock chamber receives a wafer from atmospheric pressure. The vacuum pressure of the transfer chamber/buffer will increase once it is opened to receive a wafer. Thereafter, the transfer chamber will be pumped by a vacuum pump to return to the vacuum pressure.

Sometimes long recovery times may be needed for the transfer chamber to return to the vacuum pressure, once the transfer chamber is closed and receives the wafer from the load lock chamber. Such long recovery times can be detrimental to throughput. A recovery time associated with the transfer chamber/buffer returning to a low vacuum pressure should be conceivably as short as possible so manufacturing deposition processes can occur in vacuum conditions.

Additionally, cluster tools can include chambers with several different valve separation configurations. Different chambers can be separated by valves to maintain vacuum conditions, such as a load lock chamber and a transfer chamber. Valve arrangements can be costly. These configurations can also include an isolation valve that separates a vacuum pump from a chamber, such as a transfer chamber, or a valve that separates a rough pump from a load lock chamber. Numerous sets of valves are costly and can drive up the overall cost of the cluster tool. Moreover, each valve is often controlled in a precise manner to open and close to affect a wafer transfer. Valve control is also costly and may increase the overall operation cost of the cluster tool.

Further, regeneration operations often can result in a suspension of the manufacturing processing to remove materials from a primary pumping surface of a cryogenic pump. These regeneration operations can also decrease throughput of the cluster tool.

In one embodiment, a cluster tool has a transfer chamber, a load lock chamber, and an adaptor configured to be coupled between the transfer chamber and the load lock chamber. The adaptor has an adaptor housing with an interior space. This includes an entrance with a first valve and an exit with a second valve. The adaptor housing forms a substrate path through the interior space. The first valve connects the interior space and the load lock chamber. The second valve connects the interior space and the transfer chamber. A cryogenic surface is associated with the adaptor and is configured to selectively evacuate the interior space. A wafer is adapted to be moved through the first valve and through the adaptor housing along the path and configured to be moveable through the exit and into the transfer chamber once the second valve is opened.

In another embodiment, there is provided a method of evacuating a cluster tool having a load lock chamber connected to a transfer chamber. The method provides that an adaptor that is located between the load lock chamber and a transfer chamber. A wafer is inserted into the load lock chamber and the load lock chamber is pumped. The transfer chamber is pumped from the adaptor and the wafer is passed through the load lock chamber, through the adaptor, and to the transfer chamber. The wafer can be transferred in one step or two steps from the load lock chamber through the adaptor, and to the transfer chamber. Thereafter, the transfer chamber can be pumped from a second adaptor. Both the transfer chamber and the load lock chamber can be pumped from the adaptor, or the transfer chamber can be pumped from the adaptor and the load lock chamber can be pumped from the load lock chamber.

The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention.

FIG. 1 shows a perspective view of a cluster tool having a facet adaptor according to the present invention;

FIG. 2A shows a top schematic view of the cluster tool of FIG. 1 ;

FIG. 2B shows a prior art configuration of a cluster tool;

FIG. 2C shows another prior art configuration of a different cluster tool;

FIG. 2D shows another schematic view of the cluster tool of FIG. 2A ;

FIG. 3A shows a load lock chamber connected to the facet adaptor and the facet adaptor connected to a transfer chamber, which is connected to a process chamber;

FIG. 3B shows another embodiment of the facet adaptor having a wafer holder;

FIGS. 4A and 4B show rear and front perspective views of the facet adaptor of FIG. 3A ;

FIG. 5 show another embodiment of the present cluster tool with a first facet adaptor and a second facet adaptor sharing a compartment having a common cryogenic pump;

FIG. 6A shows pressure plots of a transfer chamber and a load lock chamber over a sequence of operation of the cluster tool of the present disclosure as compared with the operation of a cluster tool of FIG. 2C ;

FIG. 6B show a pressure plot over a sequence of operation of a prior cluster tool shown in FIG. 2B ; and

FIG. 7 shows a top schematic view of another embodiment of the cluster tool having a facet adapter being located between a process module, and a transfer chamber.

A description of preferred embodiments of the invention follows.

Turning now to FIG. 1 and 2A , there is shown a first embodiment of the present disclosure of a cluster tool 10 for use in ultrahigh vacuum chemical vapor deposition (“CVD”) manufacturing. The cluster tool 10 includes a transfer chamber 15 including a number of faces 20 . Located on an end of the transfer chamber 15 are provisions for mounting a number of process chambers 25 ( FIG. 2A ). These process chambers 25 mounted to these locations would be configured for performing one or more manufacturing operations on a wafer 100 .

Turning to a top schematic view shown in FIG. 2A , the cluster tool 10 has, disposed in the transfer chamber 15 , a wafer handling robot 30 . Robot 30 is disposed in a centermost portion of the transfer chamber 15 for automatically transferring a wafer 100 between various chambers. The wafer handling robot 30 is configured to move the wafer 100 from a load lock chamber 40 a to the transfer chamber 15 , and subsequently to pick and place the wafers 100 in the process chambers 25 . Although, shown with six wall faces 20 , one of ordinary skill in the art should appreciate that this configuration is not limiting, and the transfer chamber 15 may be formed with any number of faces 20 .

The cluster tool 10 also includes a first load lock chamber 40 a and a second load lock chamber 40 b . Although shown with two load lock chambers 40 a , 40 b , this number is not limiting, and the cluster tool 10 may be formed with any number of load lock chambers 40 a , 40 b . The first and second load lock chambers 40 a , 40 b preferably have valves to selectively open and close the load lock chambers 40 a , 40 b from ambient conditions. In operation, a wafer 100 will be transferred through the first load lock chamber 40 a and into the transfer chamber 15 . Once the wafer 100 is located in the transfer chamber 15 , wafer handling robot 30 moves the wafer 100 into the process chamber 25 for further operations. Likewise, at the conclusion, another wafer 100 will be sequentially transferred through the second load lock chamber 40 b and into the transfer chamber 15 . Once the second wafer 100 is located in the transfer chamber 15 , wafer handling robot 30 moves the wafer into another process chamber 25 .

The present cluster tool 10 preferably has an adaptor that acts as a buffer that permits the transfer chamber 15 to recover to a desired vacuum pressure, or a pressure of 10 −7 Torr, in a rapid manner, once the transfer chamber 15 receives a wafer 100 . The present cluster tool 10 has the buffer located between a first load lock chamber 40 a and a transfer chamber 15 to prevent the pressure in the transfer chamber 15 from spiking or otherwise rising too quickly relative to an example where the transfer chamber 15 is opened directly adjacent to a load lock chamber 40 a , 40 b without any buffer. In that regard, the load lock chamber 40 a having a higher pressure (since it communicates with ambient, and is subsequently pumped by a rough pump to a rough pump pressure) will likely increase the transfer chamber pressure during transfer of the wafer 100 . Moreover, the present cluster tool 10 preferably decreases a total amount of valves that are present in the cluster tool 10 relative to prior cluster tool embodiments.

Turning to FIG. 2B , there is shown a prior art configuration of a transfer chamber T C connected to load lock chambers LLC 1 , LLC 2 at each end of the transfer chamber T C . FIG. 2B shows a prior art configuration for comparison purposes. In this embodiment, a first load lock chamber LLC 1 is connected to the transfer chamber T C using a first valve V 1 . Likewise, a second load lock chamber LLC 2 is connected to the transfer chamber T C using a second valve V 2 . Disposed in the transfer chamber T C is a vacuum pump V P that is connected to the transfer chamber T C by a third valve V 3 . The vacuum pump V P evacuates the transfer chamber T C . Here, a costly isolation valve V 3 connects the transfer chamber T C to the vacuum pump V P .

In this embodiment, the load lock chambers LLC 1 , LLC 2 each communicate with atmospheric pressure. The load lock chambers LLC 1 , LLC 2 also include a rough pump Rp 1 , Rp 2 that pumps the load lock chambers LLC 1 , LLC 2 from ambient to a rough pump pressure. Once a first valve V 1 is opened, to transfer the wafer from the first load lock chamber LLC 1 to the transfer chamber T C , the pressure in the transfer chamber T C will spike or otherwise increase from the vacuum pressure of 10 −7 Torr to a relatively higher pressure since the first load lock chamber LLC 1 communicates with a rough pump pressure attributed to the rough pump RP 1 . Once the first valve V 1 is closed, then the opened isolation valve V 3 permits the vacuum pump V P to evacuate the transfer chamber T C or return the transfer chamber T C back from a relatively higher pressure to the vacuum pressure of 10 −7 Torr.

Turning to another prior art configuration of a transfer chamber T C connected to a pair of load lock chambers LLC 1 , LLC 2 , there is shown a configuration in FIG. 2C that attempts to prevent this condition by pumping each load lock chamber LLC 1 , LLC 2 prior to wafer transfer. This cluster tool attempts to eliminate any pressure increase above 10 −7 Torr in the transfer chamber T C during wafer transfer. In this prior art embodiment, like with the above embodiment shown in FIG. 2B , each of the load lock chambers LLC 1 , LLC 2 is connected to a vacuum pump, VP 1 , and VP 2 , and a rough pump, RP 1 , and RP 2 . The first rough pump RP 1 is connected to the first load lock chamber LLC 1 by a valve V 1 . A first vacuum pump VP 1 is also connected to the first load lock chamber LLC 1 by a second valve V 2 .

The transfer chamber T C also has a vacuum pump VP 3 connected to the transfer chamber T C using an isolation valve V 3 . A second rough pump RP 2 is connected to a second load lock chamber LLC 2 by a valve V 4 , and a second vacuum pump VP 2 is connected to the second load lock chamber LLC 2 by a fifth valve V 5 . Moreover, each of the load lock chambers, LLC 1 , and LLC 2 also includes a valve V 6 and V 7 to seal the respective load lock chamber LLC 1 , LLC 2 from the transfer chamber T C .

In this embodiment, the recovery time for which the transfer chamber T C can recover, once the valve V 6 is opened, can be less relative to the embodiment of FIG. 2B since the vacuum pump VP 1 evacuates the first load lock chamber LLC 1 prior to wafer transfer. Here, once a wafer is introduced into the first load lock chamber LLC 1 from atmospheric pressure, the rough pump RP 1 pumps the first load lock chamber LLC 1 from atmospheric pressure to a rough pump pressure. The second valve, V 2 opens and the first vacuum pump VP 1 evacuates the first load lock LLC 1 to vacuum pressure conditions of the transfer chamber T C .

Once the first load lock chamber LLC 1 is sufficiently evacuated, then the sixth valve V 6 will open to transfer the wafer from the first load lock chamber LLC 1 to the transfer chamber T C . Similar operation occurs with the second load lock chamber LLC 2 . Operation of the cluster tool 10 of the FIG. 2C embodiment has certain disadvantages since there are numerous costly valves that separate each vacuum pump VP 1 , VP 2 , VP 3 and respective chambers LLC 1 , LLC 2 , and T C and other valves V 6 , and V 7 to separate the chambers themselves. Further, there are also additional valves V 1 , and V 2 that separate the rough pumps RP 1 , and RP 2 from the respective load lock chambers LLC 1 , LLC 2 . These numerous valves can be very costly and drive up the overall cluster tool installation cost. Operating the cluster tool by controlling these numerous valves in a precise manner can also be costly.

Turning now to FIG. 2D , there is shown an embodiment of the present cluster tool 10 . The cluster tool 10 includes a first facet adaptor F 1 that is placed between two chambers, or between a transfer chamber T C and a first load lock chamber LLC 1 . The first facet adaptor F 1 includes a valve V 1 between the first facet adaptor F 1 and the first load lock chamber LLC 1 and valve V 2 located between the first facet adaptor F 1 and the transfer chamber T C . Second facet adaptor F 2 includes a valve V 3 between a second facet adaptor F 2 and the transfer chamber T C and a valve V 4 positioned between the second facet adaptor F 2 and the second load lock chamber LLC 2 .

In this manner, a vacuum pump VP 1 communicates with the first facet adaptor F 1 and is sealed from the first load lock chamber LLC 1 and the transfer chamber T C . Thus, the first facet adaptor F 1 can use inexpensive valves V 1 , V 2 and provide a buffer to the transfer chamber T C , since once the transfer chamber T C is opened, there will not be a dramatic pressure increase in the transfer chamber pressure T C from the vacuum pressure of 10 −7 Torr.

A recovery time to go back to conditions in the transfer chamber T C before the second valve V 2 was opened can occur much quicker in the transfer chamber T C as shown in FIG. 2B , where the rough pump pressure cause the transfer chamber pressure to spike. This is relative to an instance where the transfer chamber T C is directly connected to the first load lock LLC 1 . The second facet adaptor F 2 includes a similar configuration. Having both facet adaptors F 1 , and F 2 , the cluster tool 10 does not need costly isolation valves between the vacuum pump VP 1 and the housing of the facet adaptor F 1 , or a valve between the second vacuum pump VP 2 and the housing of the second facet adaptor F 2 . Further, a vacuum pump in the transfer chamber T C can be eliminated and the vacuum pump Vp 1 of the first facet adaptor F 1 and/or the second vacuum pump Vp 2 in the second facet adaptor F 2 can be used to evacuate the transfer chamber T C .

This is also advantageous since the facet adaptors F 1 , F 2 can undergo a regeneration operation while closing the respective valve (V 2 or V 3 ) to the transfer chamber T C , while the other facet adaptor is available for use. This permits the facet adaptors F 1 , F 2 having one vacuum pump Vp 1 , Vp 2 to undergo regeneration operation(s) as needed, without taking the entire cluster tool off line, to ensure continuous cluster tool operation. With regard to the embodiments of FIG. 2B and 2C , the transfer chamber having a vacuum pump Vp ( FIG. 2B ) or VP 3 ( FIG. 2C ), the entire tool must be taken off line to regenerate that vacuum pump Vp ( FIG. 2B ) or VP 3 ( FIG. 2C ). With the present system of FIG. 2D , vacuum pump VP 1 may be taken offline and the cluster tool may use vacuum pump VP 2 to evacuate the transfer chamber. Also, vacuum pump VP 2 may be taken offline and the cluster tool may use vacuum pump VP 1 to evacuate the transfer chamber. This ensures continuous operation and this permits the remaining facet adaptor F 2 having the vacuum pump Vp 2 to continue operation during a regeneration operation of the first vacuum pump Vp 1 without taking the entire cluster tool off line to ensure continuous cluster tool operation. Before, with a vacuum pump located in the transfer chamber ( FIGS. 2B and 2C ), the entire cluster tool had to be taken off line for a regeneration operation. This may result in substantial down time. Other pumps are also envisioned, such as a turbo pump, high vacuum pump, or water vapor pump, and the present cluster tool 10 is not limited to any specific pump.

As shown in FIG. 2A , the cluster tool 10 according to the present disclosure includes a first facet adaptor 60 and a second facet adaptor 65 with each of the facet adaptors 60 , 65 corresponding to a respective load lock chamber 40 a , 40 b . The first facet adaptor 60 includes a first facet adaptor housing 70 with an entrance 75 and an exit 80 .

The entrance 75 faces the first load lock chamber 40 a . The exit 80 faces the transfer chamber 15 . The first facet adaptor 60 further includes a wafer path 70 a disposed through the first facet adaptor housing 70 . The first facet adaptor 60 also is isolated from the transfer chamber 15 and the first load lock 40 a , respectively by a first valve 85 and a second valve 90 . In one embodiment, the first and the second valves 85 , 90 are slit valves; however, the cluster tool 10 is not limited to slit valves, and the first facet adaptor 60 may include gate valves, any other suitable inexpensive valve arrangement known in the art suitable to isolate a volume of the first facet adaptor 60 from the transfer chamber 15 and the first load lock 40 a . It should be appreciated that in another embodiment, the valves 85 , 90 may be suitable to form a very thin opening complementary to the thickness of the wafer 100 , which is configured to permit a wafer 100 to pass through path 70 a quickly, and then permit the valves 85 , 90 to close.

In one embodiment, the wafer 100 may be pulled directly from the first load lock 40 a and into the transfer chamber 15 through path 70 a by robot 30 . In another alternative embodiment shown in FIG. 3B , the first facet adaptor 60 further includes a wafer holder 70 ′. The wafer holder 70 ′ is a stand or similar structure that permits the wafer 100 to rest or reside in the first facet adaptor 60 . In this aspect, a second wafer handling robot (not shown) may be used to introduce the wafer 100 into the first facet adaptor 60 . Thereafter, the wafer handling robot 30 in the transfer chamber 15 may be configured to sequentially withdraw the wafer 100 from the first facet adaptor 60 on wafer holder 70 ′ and move the wafer 100 into the transfer chamber 15 . It should be appreciated that the wafer holder 70 ′ is a support structure that is disposed in the first facet adaptor housing 70 for which a wafer 100 may be rested thereon prior to being introduced into the transfer chamber 15 . In one embodiment, the wafer holder 70 ′ is a small platen with a three point stand that supports the wafer 100 .

Turning now to FIG. 3A , there is shown a side cut away view of the first load lock 40 a connected to the first facet adaptor 60 , which is connected to the transfer chamber 15 along face 20 , with the wafer holder 70 ′ removed. The first facet adaptor 60 also includes a pressure sensor 105 a to detect the pressure therein and also has a cryogenic refrigerator (not shown) connected to a cryogenic pump 110 . A cryogenic pump 110 that may be used in connection with the present disclosure is described in detail in U.S. Pat. No. 5,782,096 to Bartlett et al., which is incorporated by reference in its entirety.

Generally, cryogenic pump 110 may include a low temperature second stage array, usually operating in the range of 4 degrees to 25 degrees Kelvin, as the primary pumping surface. Other primary pumping surfaces are also envisioned, such as, for example, a turbo-pump, water vapor pump, high vacuum pump or any other suitable pump known in the art. This primary pumping surface is surrounded by a high temperature cylinder, usually operated in the temperature range of 50 degrees to 130 degrees Kelvin, which provides radiation shielding to the lower temperature array. The radiation shield (not shown) generally comprises a housing which is closed except at a frontal array positioned between the primary pumping surface and the chamber to be evacuated. This higher temperature, first stage, frontal array serves as a pumping site for higher boiling point gases such as water vapor. High boiling point gases, such as water vapor, are condensed on the frontal array. Lower boiling point gases pass through that array and into the volume within the radiation shield and condense on the second stage array. A surface coated with an adsorbent such as charcoal or a molecular sieve operating at, or below, the temperature of the second stage array may also be provided in this volume to remove the very low boiling point gases. With the gases thus condensed or adsorbed onto the pumping surfaces, only a vacuum remains in the facet adaptor 60 . Typically a two stage refrigerator having a cold finger, which extends through the radiation shield is used, and the cold end of the second, coldest stage of the refrigerator is at the tip of the cold finger. The primary pumping surface, or cryopanel, is connected to a heat sink at the coldest end of the second stage of the cold finger. This cryopanel may be a simple metal plate, a cup or a cylindrical array of metal baffles arranged around and connected to the second stage heat sink. This second stage cryopanel may also support low temperature adsorbent. The radiation shield (not shown) is connected to a heat sink at the coldest end of the first stage of the refrigerator. Various vacuum pumps may be used and the present disclosure is not limited to any specific high, or ultrahigh vacuum pump. The facet adaptor 60 may also communicate with a water vapor pump, or a turbo pump. The cryogenic pump 110 may be located separate from the first facet adaptor housing 70 , or alternatively, the housing 70 may be enlarged so that the vacuum pump 110 is integrated with the first facet adaptor housing 70 .

The cryogenic pump 110 may evacuate the transfer chamber 15 , or alternatively an additional, secondary ultrahigh vacuum pump (not shown) may be positioned in the transfer chamber 15 to evacuate the chamber 15 . With the cryogenic pump 110 integrated into the facet adaptor housing 70 , extensive downtime associated with a regeneration operation may be eliminated. In this aspect, the cryogenic pump 110 may undergo a regeneration operation, while another cryogenic pump for another facet adaptor remains to evacuate the transfer chamber. This may facilitate continued manufacturing operations in the transfer chamber while the first cryopump 110 undergoes a regeneration operation. In another embodiment, cryopump 110 may be sufficiently rated to evacuate multiple chambers.

Turning now to FIGS. 4A and 4B , there is shown a perspective view of a first facet adaptor or buffer 60 having an entrance 200 and an opposite exit 205 with the facet adaptor 60 disconnected from the load lock chamber 40 a and the transfer chamber 15 . The first facet adaptor 60 is shown as having a wafer path 210 being disposed therethrough. In FIG. 4A , the first facet adaptor 60 includes a first slit valve 85 that is partially closed over an entrance 200 . On an opposite side shown in FIG. 4B , another second valve is retracted (not shown) and in an open positioned. Each valve 85 , 90 is connected to a pneumatic device along supply lines 185 , 190 for opening and closing the first slit valve 85 and the second slit valve 90 . The first facet adaptor 60 preferably also has a suitable interior space 215 for forming path 210 . The interior space 215 is suitably large such that a wafer 100 ( FIG. 4B ) may be passed through the housing 70 . As mentioned, interior space 215 can be suitably large, such that a wafer stand 70 ′ is also housed therein.

Turning now to FIG. 5 , there is shown another embodiment of a cluster tool according to the present invention generally represented by reference numeral 10 ′. In this embodiment, instead of having a cryogenic pump 110 with a cryogenic refrigerator associated with each facet adaptor 60 , 65 as shown in FIG. 2 , the cluster tool 10 ′ may be configured so the facet adaptors 60 , 65 share a common cryogenic pump 60 b and cryogenic refrigerator. In this embodiment, the transfer chamber 15 ′ includes a number of faces 20 ′ similar to the embodiment discussed above. The cluster tool 10 ′ can include process chambers 25 ′, a first load lock chamber 40 a , and a second load lock chamber 40 b.

In this embodiment, the cluster tool 10 ′ includes a first facet adaptor 60 ′ and a second facet adaptor 65 ′ that share a common housing 60 a . Housing 60 a is positioned between the adaptors 60 ′, 65 ′. The cluster tool 10 ′ may be manufactured with other similar housing(s) disposed between other adaptors located on the cluster tool 10 ′. The common housing 60 a includes a common cryogenic pump 60 b that can selectively evacuate either the first facet adaptor 60 ′ or the second facet adaptor 65 ′ and may be configured with valves 60 c , 60 d on either side of the housing 60 a.

Cryogenic pump 60 b may evacuate either the first facet adaptor 60 ′, the second facet adaptor 65 ′, or both and/or other chambers of the cluster tool 10 ′ (such as the transfer chamber 15 ). The cluster tool 10 ′ of FIG. 5 advantageously uses less hardware to evacuate multiple wafer paths.

Turning now to FIG. 6A , there is shown two pressure plots during a sequence of operation of a wafer traversing from the load lock chamber 40 a through the first facet adaptor 60 and into the transfer chamber 15 ( FIG. 2A ). A first plot shows a load lock chamber pressure. A second plot shows a transfer chamber pressure. The slit valve 85 on the load lock side of the facet adaptor 60 is closed while the slit valve 90 on the transfer chamber side of the facet adaptor 60 is opened during time interval t 1 . Here, the wafer is at atmospheric pressure in the load lock chamber 40 a . During time interval t 2 , the load lock chamber 40 a is “rough pumped” from atmospheric pressure to a pressure of 1×10 −3 Torr.

During interval time t 2 , the slit valve 85 (on the load lock chamber side of the facet adaptor 60 ) is closed while the slit valve 90 (on the transfer chamber side of the facet adaptor 60 ) is opened. During interval time t 3 , the slit valve 85 on the load lock side of the facet adaptor 60 is opened, and the slit valve 90 on the transfer chamber side of the facet adaptor 60 is closed.

During time interval t 4 , both slit valves 85 , 90 are opened. During time interval t 4 , the wafer handling robot 30 manipulates the wafer 100 from the load lock chamber 40 a through the facet adaptor 60 and into the transfer chamber 15 . Thereafter, during time interval t 5 , the load lock chamber slit valve 85 is closed while the transfer chamber slit valve 90 is opened and the pressure in the load lock chamber 40 a returns to atmospheric pressure. Notably, the pressure of the transfer chamber 15 is held relatively in a range of a vacuum pressure (Torr) due to buffering function of the facet adaptor 60 during time intervals t 3 and interval t 4 and the pressure in the transfer chamber 15 does not substantially spike or increase, but remains at the vacuum pressure.

Contrast the above operation with FIG. 6B . FIG. 6B shows two pressure plots over time for a prior art cluster tool configuration shown in FIG. 2B for comparison purposes. The first plot shows the pressure reading of a first sensor in the load lock chamber LLC 1 . The second plot shows the pressure reading of a second sensor in a transfer chamber T C . First pressure plot shows the rough pumping pressure plot sequence from atmospheric pressure to a rough pump pressure. Later, vacuum pump V P evacuates the transfer chamber T C and brings the pressure down from 25×10 −3 Torr to 10 −7 Torr.

Once a valve V 1 is opened (that separates the transfer chamber T C and the first load lock chamber LLC 1 ) the pressure in the transfer chamber T C rises at sequence B from 10 −7 Torr and spikes upwardly to 25×10 −3 Torr. After wafer transfer takes place and the valve V 1 is closed, vacuum pump V P evacuates the transfer chamber T C back to the transfer chamber pressure 10 −7 Torr (as shown by sequence C).

The present cluster tool 10 avoid this costly time for the transfer chamber to recover to the vacuum pressure of 10 −7 Torr, after wafer transfer, by providing a buffer. Moreover, the present cluster tool 10 provides this without costly additional valves. This quick recovery time increases throughput of the cluster tool 10 .

Turning now again to FIG. 6A , there is shown a graph of a pressure plot of a load lock chamber pressure of the tool configuration of FIG. 2D . During time interval t 1 , the first load lock chamber LLC 1 is at atmospheric pressure, and both valves V 1 and V 2 are closed as shown on a top legend. During time interval t 2 , a rough pump Rp 1 evacuates the load lock chamber LLC 1 from ambient to a rough pump pressure. During time interval t 3 , a valve V 2 opens and a vacuum pump Vp 1 evacuates the load lock chamber LLC 1 further to a vacuum pressure of 10 −7 Torr while valve V 2 is closed. Thereafter, during time interval t 4 , a valve V 2 opens for the wafer transfer to take place, and then valve V 1 closes once the wafer is correctly positioned in the transfer chamber T C during time interval t 5 . During time interval t 5 , the valve V remains closed and the pressure returns in the load lock chamber LLC 1 to atmospheric pressure.

The cycle is then repeated in a continuous fashion in order to sequentially move wafers from atmosphere and high vacuum conditions of the process chambers. In this embodiment a single high vacuum pump V 1 performs the functions of the then high vacuum pumps shown in prior art FIG. 2C .

FIG. 7 shows another exemplary embodiment of the present cluster tool 310 . In this embodiment, a first adaptor 360 is placed between the process module 325 a and the transfer chamber 315 . A second adaptor 365 is placed between the process module 325 b and the transfer chamber 315 . The first adaptor 360 includes valves 385 , and 390 and second adaptor 365 includes valves 385 , 390 . The first and second adaptors 360 , 365 can act as a buffer and isolate, and pump the transfer chamber 315 or the process modules 325 a , 325 b , as previously discussed. In this aspect, one process module 325 a or 325 b can be selectively isolated from the transfer chamber 315 while the other process module 325 a or 325 b can be used for continuous cluster tool operations. It should be appreciated that in each of the embodiments discussed above the adaptors 360 , 365 may include a single pump or work together with multiple pumps. Various pump configurations are possible and within the scope of the present disclosure, and the disclosed tool are not limited to any specific pumps.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.